Description of Tests and Diagnostic Standard
Vaginal swabs were collected during a speculum examination, placed into saline, and sent to the on-site laboratory. A wet preparation was performed with fluid expressed from the swab by placing a drop onto a glass slide and examining it under the microscope for motile trichomonads within 20 min of specimen collection. The residual specimen volume was aliquoted and stored at 4^oC. The Xenostrip-Tv test (Xenotope Diagnostics, San Antonio, TX) was performed within 24 h by adding sample buffer to the specimen, placing the absorbent end of the nitrocellulose membrane test strip into the tube, and reading the results at 10 min. If T. vaginalis was present, a complex consisting of T. vaginalis antigens and mouse antibodies that were conjugated to red particles on the strip was formed. A secondary anti-mouse capture antibody bound the complex, forming a red line. A second capture line served as a positive control to monitor assay performance. If no red line appeared or background color made reading impossible, the results were considered invalid. DNA was extracted from specimens using the QIAamp DNA mini kit (QIAGEN, Valencia, CA) according to the manufacturer‚s instructions. PCR amplification was performed using primers TVK3 and TVK7, which amplify a 261 bp sequence of a T. vaginalis repeat DNA fragment. Specimens positive by the PCR assay and negative by either the Xenostrip-Tv test or the wet preparation were tested with a confirmatory PCR amplification performed using primers TVA5-1 and TVA6, which amplify a 98 bp fragment. The forward primers for both PCR assays were labeled at the 5‚ ends with fluorescein phosphoramidite so that amplicon size could be determined on an ABI 310 Genetic Analyzer (PE Applied Biosystems).